Thread: Wheel

18" radius or diameter?

Diameter. Finished part will be 2" wide x 1 1/2" thick /c relieved lands on the ventral to accept heavy glass.

You'll need an auxiliary sheet to hold the center pivot for use on the router table. It might be easier to use something like this: https://www.woodworkforums.com/f88/router-compass-50372/

The workpiece, and a block to lift the pivot, could be temporarily attached to something flat. Hot-melt glue, perhaps. The router could cut the inside, the inside rabbet, and almost any outside profile using combinations of bits. All of this would be right-side-up, and easier to visualize. The "something flat" can be partially sacrificial, to allow complete shaping.

The glued finger joints should be strong enough by themselves to dispense with pegs.

Cheers,
Joe

Good job. Thank you very much for your time and advice.

Hi Wilbur, Noticed your thread soon after you posted, but decided not to comment till I had had some rest and could make positive contribution.

I have attached a couple of PDF files showing the basic layout of what i believe you want to make, and the minimum dimension details of what each segment should be.

Colour key for the PDF's is as follows

Black circles 9 inch and 7 inch radii fo finished inner and outer circles
Red circles Trim allowance of 1/8th inch inside and outside finished circles.
Green lines Segment boundaries
Blue Line Outer edge of segment

From the 1 segment sketch, the segments would need to be 7.5 inches long for a simple butt joint but longer if you were to use finger joints or similar for joining the segments. Can't suggest how much larger without knowing how you intend to join the segments and cutter dimensions etc. The segments would need to be a minimum 2.81 inches wide to give a 2 inch wide rim, again based on a butt joint but needing to increase depending on joinery method used.

Speaking of joinery, dowelling the segments together is possibly not a great idea unless you are very sure of getting at least two dowels into each joint outside the area to be routed. Would look rather sad if a dowel or dowel cavity was exposed. My father build a number of boat wheels with the segments finger jointed and never had problems, and wooden steering wheels for cars were joined the same way as well.

Basic technique would be to establish the actual segment sizes required allowing for the chosen joinery method, dimension stock and cut a set of segments and a few test pieces for settting up joinery, and machine joinery to chosen method.

The significance of the red (trim allowance) lines is that the segments should then be trimmed with a band saw or similar to the trim allowance lines before glueup. This is because you need to take very shallow router cuts to finish the ring to size as the inner and outer wall cuts will be 1.5 inches or so in height and load the router and bit. There just won't be enough power and rigidity in the system to hog out the major waste components.

You can then glue up the segments to form a the ring, and mount the ring onto a substantial backer board, say 3/4 inch ply or mdf. You will want a substantial block the same height as the ring mounted in the centre of the backer board to accomodate the pivot point for the router trammel set as well. Depending on how rigid the trammel system is, you might also need support inside and outside the ring but well clear to ensure that router bit remains square to the surface of the ring.



As to machining sequence, I would suggest;

1. Outer ring edge finished to final dimension with a large (3/4in 1/2 in shank) bit, cutting over full depth ' i.e just into the backer board.
2. Inner ring glass rebate with the same bit.
3. Outer ring upper edge treatment (roundover etc) if required
4. Inner ring edge to final dimension, again with a large (3/4in 1/2 in shank) bit, cutting over full depth ' i.e just into the backer board. I have listed his as the last cut to ensure that the cut into the backer board does not effect the other cuts by reducing its rigidity.
5. Outer ring lower edge treatment if required after removal from backer board, possibly best done on a router table if available.

Hope this helps with the project. I'm willing to rework the drawings if you indicate what you intend using for the joinery, but it might take a week or so to come up with them.

Thank you gentlemen for your replies. I am reassured and pressing on. The male/female lap joints will be hilarious to cut on the table saw. Freud makes a two-piece router set for this but I need more depth. I will build a jig for the table saw and test my math. My aluminum router table is one by four feet. The current fantasy is to sandwich the glued frame between a smaller circle of plywood and a second plywood circle with a finished edge for the pilot bearing on a 2" straight flute. The pegs through the joints perform no function as they will not be stressed. I think they look cool, same as the joints. It will live next to Ann's chair in the living room. It will be necessary to glue up the 3/4" cherry stock to the required 1 1/2" thickness.

Thank you very much for you time and trouble.

yes i think you can make cuts on ur table.

I bought a plywood disk to use for the bottom support for my carousel, 3/4" thick, 18" diameter. Double-backed tape attached it to a square sheet of 1/4" build board, cut to 18 1/2" X 18 1/2". This extra 1/4" on all sides allowed me to locate the straight sides against the fence on my table saw to cut the necessary slots in the base to receive the 1/4" patricians.
After they were cut, I turned the assembly over and located the outer edge of the disk against the pilot bearing of the straight-fluted router cutter and cut the square sides off of the build board to make it the same size as the plywood base. The resulting round build board is now the outside pattern for the picture frame/wheel that started me on this path in the first place. The math told me what the inside diameter would have to be when using 2" X 4's" for the 8-sided pictured frame. This inside diameter was drawn and cut on the build board, giving me a 1/4" thick X 18" diameter donut that was to be the pattern for the finished wheel. After building the straight-sided picture frame, it got double-backed taped to the donut. The inside and outside lands of the donut were then located against the same bearing of the of the table router to cut the inside and outside round and done.